Oxford BioMedica
Obtains Approval for TroVax® to Enter Phase
II Trials for Colorectal Cancer
Oxford
BioMedica (LSE:OXB) announced today that it had received
ethical approval from
the UK Gene Therapy Advisory Committee (‘GTAC’)
for its therapeutic cancer vaccine, TroVax, to enter
a Phase II clinical trial in patients receiving chemotherapy
for colorectal cancer. The trial is planned to start
within two months.
TroVax is designed
to stimulate a patient’s immune
system to recognise and destroy cancer cells. The product
is based on a gene that encodes a protein, known as 5T4,
which exists only on the surface of tumour cells and not
on normal cells. When this gene is expressed by Oxford BioMedica’s
highly engineered virus-based delivery system, it induces
a potent anti-tumour response. This means that cells and
antibodies of the immune system seek out the tumour cells
carrying 5T4 and destroy them.
TroVax has successfully completed a Phase I/II trial in
metastatic colorectal cancer patients and has been shown
to be safe and well tolerated in these patients. Furthermore,
TroVax was shown to be immunogenic, inducing anti-5T4 antibodies
and T-cells in 11 out of 12 patients. In addition disease
stabilisation, reduction in circulating tumour markers and
tumour necrosis was observed in some patients. These data
form the basis for moving into Phase II.
The Phase II programme is designed to maximise the speed
with which TroVax could reach a cancer market of reasonable
size. The strategy is to continue to focus on colorectal
cancer and to move quickly towards making TroVax ready for
a Phase III efficacy study. The target population will not
be the very late stage, post-chemotherapy group of the first
trial but rather the somewhat earlier patient population
receiving chemotherapy for the first time for metastatic
or inoperable disease. The rationale is that TroVax might
contribute to tumour reduction via immune system-mediated
cell killing and this could be amplified in the presence
of the cell death that is induced by chemotherapy. This would
place TroVax alongside current first-line chemotherapy and
provide a relatively simple, relatively short-term survival,
or time-to-progression, end-point. In order to get to a Phase
III study in combination with chemotherapy, a short Phase
II study is required to show that TroVax induces an appropriate
anti-5T4 response in this context. It is this study that
has been approved by GTAC.
GTAC has approved an open label Phase II trial in up to
15 patients of 5 doses of TroVax in patients receiving 5-fluorouracil,
leukovorin and irinotecan. The end-points of the trial will
be the immune response to TroVax and safety in conjunction
with this chemotherapy. Therefore the trial is expected to
last only 6 months after the recruitment of the last patient.
The Company anticipates rapid recruitment because of the
large number of patients fulfilling the entry criteria. The
protocol is designed to give immunological readouts following
vaccination before, during and just after completion of chemotherapy.
The trials will take place at the Christie Hospital in Manchester
and two other centres in the UK. The overall aim is to provide
data to finalise the design of a Phase III protocol that
could lead to product registration in 2007/8.
If TroVax is successful in this context and achieves product
registration for use in colorectal cancer patients receiving
first line chemotherapy, it could command a market of between
$0.5-1.0 billion.
Commenting on
GTAC’s approval Chief Executive, Alan
Kingsman said “ TroVax is an
exciting product and it is very pleasing to see it progressing
towards
the market. Making TroVax a potential
phase III product for 2004 should potentiate our ability
to find the right partner for this product. The Company is
also seeking approval for trials to study the use of TroVax
for other cancers as part of the strategy to broaden the
market potential of the product.”
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